Cellulose treatment and product



2,981,589 Patented Apr. 25, 1961 United States Patent 2,981,589 CELLULOSE TREATMENT AND PRODUCT Walter L. Hochner, Wilmington, Del., and Abb L. Scarbrough, Rahway, N.J., assignors to National Lead glompany, New York, N.Y., a corporation of New No Drawing. Filed May 21, 1958, Ser. No. 736,680

1 Claims. (c1. 8-1162) repellant. In general, these have consisted for the most part of various impregnating techniques whereby waterrepelling agents, such as oils, waxes, synthetic resins or similar agents were deposited on the fiber and in the interstices between fibers, either to seal up the pores and thus prevent passage of water therethrough, or to impart a hydrophobic character to the surface, thus retarding the passage of moisture by the utilization of surfacetension efifects.

" These methods, however, suffered from certain disadvantages. The type of treatment which depended on a sealing of the pores was undesirable for many purposes because it made the fabric impervious to passage of air as well, so that the fabric was unable to breathe. Treatments which depended on the imparting of a hydrophobic surface to the fiber overcame this disadvantage, but consisted primarily of impregnations or deposits of synthetic resins which were soluble in organic solvents and hence not capable of withstanding dry-cleaning.

An object of this invention, therefore, is to provide ;an improved process for treatmentof fibrous cellulosic materials.

Another object is to provide an improved process for imparting hydrophobic characteristics to fibrous cellulosic materials. A further object is to provide a method for imparting water-repellancy to cellulosic fabrics. A still further object is to impart, to a cellulosic fabric, water-repellent properties which are not methyl groups and treating said partially carboxyalkylated cellulose with a quaternary ammonium halide having at least one alkyl group containing at least 12 carbon atoms.

This invention also contemplates, as a new article of manufacture, a modified cellulosic material characterized in that between one-third and one-fifteenth of the original anhydroglucose units of said cellulose arerepresentable by the formula GHmRoooNR',

wherein R represents a divalent alkyl hydrocarbon radical containing from 1 to carbon atoms, and the four 2 R' groups are monovalent alkyl hydrocarbon radicals which may be the same or diflerent, each R group containing from 1 to 18 carbon atoms, atleast one of said R groups containing at least 12 carbon atoms.

u The carboxyalkylation of the cellulose must be partial, and within the range above specified If more than about /3 of the hydroxymethyl groups of the original cellulose structure are carboxyalkylated, the cellulose itself becomes watersol uble, or at least colloidally waterdispersable, and is unsuited to the production of a hydrophobic modified cellulosic material. If, on the other hand, less than about 5 of the original hydroxymethyl groups are carboxyalkylated, there are not enough car; boxyalkyl groups in the molecule to react with the neces sary quantity of amine salt, and the degree of waterrepellancy will be impaired.

The carboxyalkylation of the hydroxymethyl groups is essential. It has been attempted to introduce the amine group into the cellulose molecule in a slightly different fashion, by oxidizing the hydroxymethyl group with N0 thereby converting it to a carboxyl group, and then forming theaminesalt ofthat carboxyl group.

This procedure producesa measurable, but much paired and unsatisfactory degree of water-repellancy. The reason for this difference in reactivity between a simple COO H group and a CH O- RCOOH group according to the invention is not fully established, but is believed to be a result ofsteric effects.

The term carboxyalkoxymethyl, as used. herein to describe the group resulting from modification of the hydroxymethyl group of the original cellulose molecule, is employed for the sake of simplicity, and is intended to embrace both the carboxyalkoxymethyl group itself,

stituted alkanoic acid containing up'to about 5 carbon atoms may be employed, but it is preferable, primarily for economic reasons, to employ short-chain, singly-substituted acids such as monochloroacetic acid. Similarly, any alkali may be employed but there is no advantage in using the relatively expensive potassium hydroxide or the other even more expensive alkalis, sodium hydroxide being quite adequate for the purpose. Alkaline earths,

such as Ba(OH) Ca(OH) etc. are, however, insufliciently alkaline. l

The degree of carboxyalkylation of thecellulose is controlled by the reaction conditions, particularly the concentrations of acid and alkali and the time and temperature at which the reaction is carried out. "it

has been found that with a solution of 2% sodiumhY- droxide and 2% monochloroacetic acid in water approximately A; of the hydroxymethyl groups are carboxyalkylated in 15 minutes at 50 C. These reaction conditions are illustrative and obviously may be varied, as

will be obvious to those skilledin the Thus, the concentration of alkali may be as low .as about 1% or as high as about 10%. The higher concentrations of alkali favorrnore rapid and complete reaction, and also favor a partial mercerization, involving other hydroxymethyl groups than those which are carboxyalkylated. The mercerization effect takes place as a side reaction which is ordinarily not an undesirable one. Similarly, the concentration of the acid may vary between about 1' andabout10%,-the higherconcentrafreestanding 'fioreomrilek and are 'carboxy'alkylation.

The temperature and the time are mutually interdependent to some extent; thus, with conditions otherwise the sa'fne, the neared degree of 'ea'rboxy'a'lkylation can h e-achieved by a few nfi-nlite's"-treattrient at temperatures a'lidveSOC. *and up to 'abut l C., or by a protracted tfeat'rnent for 'se'veral hours at room temperature (say-25 C.), or Slightly higher. At the higher temperaitiir'bs, the progress bf-the reaction is, naturally, more Hifli'cult to control precisely, while at the lower tempera- '-'tiii'es, treatment tirries tend to be unduly extended, and it'h'as been foundr'riost convenient to operate at intermediate temperatures.

lhe cellulosic material "er'nployed according to this invention 'ma'y be in its natural state or may have undergone :a previous 'm'odification according to known methods. For example, the original cellulose may have been"'partiall.'y acetylated, or partially nitrated, or converted to viscose or cupram'rrion'ium rayon, etc. It is essential, however, that at least of the original CH 'OH group's be pre's'ent, either unmodified or re- "generated. Inth'is connection, it 'should be noted that the degreeof'carboxyalkylation Specified above, viz. from to% "of the hydroxym'ethyl groups, is based on the hydroxymethyl groups originally present in the cellulose molecule, not of those remaining after any such prior treatment.

' When'the cellulose hasbeen partially carboxyalkylated as just described, 'th'e'resulting carboxyalkyl groups are cohverted to quaternary amine salts by metathetical exchange with a su'itable quaternary amine halide. As 'npte'a ab'ove,the carhox'y'alkyl*grouprriay be inthe alkali sfaltfformfez'g. =R COONa, in which "case the alkali ti'ietal ion is'replaced hy thequater'nar'y ammonium cation, forming an alkali halide lay-product. Where the carb oxyalkyl group ispfesent in the acid form, i.e. -R--COOH,"the"r'eaction"is the same, except that the by-product is a hydrohalic acid.

The quaternary ammonium salt is of the form (R mmwhere the -R' groups are monovalent alkyl hydrocarbon fradi c'als containing; from -1 -to 18 carbon atoms, and may be the same or different and X is an ionizable anion, preferably-a halide ion. Among the Rgroups, it is es- --sential-that at least one of them be a long-chain radical -moniumsalts therefore include, as a few random examples, dodecyl trimethyl ammonium chloride, tetradecyl -triethylammonium bromide, hexadecyl triisopropylam- ;rn onium iodide, octadecyl tributylammonium sulfate, etc. Particularly preferred quaternary ammonium salts, conytaining at leasttwo long-chain radicals, include didodecyl .dimethylammonium chloride, ditetradecyl diethylam- .monium bromide, dihexadecyl diisopropylammonium .iodide, dioctadecyl dimethylammonium chloride, tri- .dodecyl monomethylammonium chloride, tritetradecyl monoethylammonium bromide, trihexadecyl monoisopropylammonium iodide, trioctadecyl monomethylammonium chloride, tetradodecylammonium chloride, tetrahexadecylammonium bromide, tetraoctadecylammonium chloride, tetracontylammonium-sulfate, etc.

The reaction between the quaternary ammonium salt -and the partially carboxyalkylated cellulosic material rproceeds without difiiculty and may be carried out at any convenient temperature between room temperature and the boiling point-of the solvent (ordinarily water).

The-reaction-is rapid and is complete within a few minute's, even at room temperature. Although this reaction may be carried out as asepar-ate-step, completely apart from the carboxyalkylation step, it is more convenient, and for reasons which are not known, also more eflective to carry out the two reactions simultaneously, by dissolving the quaternary ammonium salt in the same solution of acid and alkali that is used to effect the carboxyalkylation. Thus, instead of-using a solution of 2% NaOH and 2% monochlor'oacetic acid to carboxymethylate, as described above, and subsequently usin'g"a--s'ep'- arate solution of a quaternary ammonium halideto'convert the carboxymethyl group to its quaternary ammonium salt, it has been found effective to employ a solution containing 2% NaOH, 2% monochloroacetic acid and 2% dioctadecyldimethylammonium chloride, and perform both steps in a single operation. The reaction conditions are not affected by the presence of the quaternary ammonium salt and, as above, may suitably consist of a 15 minute treatment at 50 C. Also,'the concentration of the quaternary ammonium salt in th'e solution is not critical; it is limited only by solubility "on the one hand and the necessity 'of havingsutfici'ehtammonium salt to react with the earboxyalk'yl groups on the other.

In order to illustrate more fully the nature of this invention, the following examples are presented:

Example I A treating solution was prepared by dissolving 2kg. of NaOH, 2 kg. of monochloroac'etic acid, and 2 kg. of dioctadecyl dimethylammoniurn iodide iri 'wate'r, "and diluting the solution to a volirme'oflOOzl. Thesolution 'was heated to'50'C. *Asainple "of cotton twill, Weighing 8.2 oz. per square yard, was steeped in the heated solution for 15 minutes, then withdrawn, washed'with water, and dried. The dried cloth 'was then "subjected to a water-repellancy test as described in the Technical Manual and Year Book of the American Association of Textile Chemists and Colorists, v' olurne 2f7, 1951, Resistance to Wetting, Standard Test Method 22-41,

page 133. p p

The treated cotton'twill tested in this manner obtained a rating of 70. By comparison, anuntreated sample of the same cloth was also subjected to the same test and was completely wetted with arating of zero.

The treated material was laundered several times and subjected, after each la'undering,to the same above mentioned wetting test. It was found that the treated material maintained its rating of 70 after each laundering.

Example II dissolving the free acid therein in a known excess of standard base, and titrating the excess base with phenolphthalein. The degree of carboxyalkylati'on was thus determined to be of the hydroxymethyl "groupsoriginally present. a

The remainder of the treated clothiwas'then immersed in a 2% solution of dodecyl trimethylammonium chloride for 15 minutes at 50 C. The cloth was then rinsed'with Water and dried.

The water repellancy test of Example I thenre peated using the treated cloth of this Example II. The treated cloth of the present example obtained a rating of 60. The treated material of this example was subjected to several launderings and after each laundering, the water'repellancy test "was repeated. It was found that the treated material of this example maintained its rating of 60.

Example III The procedure of Example II was repeated, but the cotton twill Was placed in a 30% monochloroacetic acid solution for six minutes, the excess acid squeezed out, and the cotton twill was then placed in a 50% sodium hydroxide solution at 80 C. for two minutes.

The degree of carboxyalkylation was determined as in Example II, and was ascertained to be /3 of the hydroxymethyl groups originally present.

The remainder of the treated cloth was then subjected to the same procedure as in Example II, except that the tetradecyl triethylammonium bromide was used in place of the dodecyl trimethylammonium chloride used in Example II. I

The water repellency test of Example I was then repeated using the treated cloth of this Example III.

The treated cloth of the present example obtained a rating of 80. The treated material of this example was subjected to several launderings and after each laundering, the water repellency test was repeated. It was found that the treated material of this example maintained its rating of 80.

Example IV The procedure of Example I was repeated, except that an equivalent amount of omega monochloropentanoic acid was used in place of the monochloroacetic acid used in Example I.

The treated cotton twill was subjected to the same tests as in Example I. A rating of 70 was obtained both before and after laundering.

The process of this invention is simple and economical.

' It is effective to provide, in cellulosic materials, hydrophobic properties and Water-repellency which are not subject to removal by exposure to organic solvents. It is applicable to cellulosic materials in general, including fabrics such as cotton, linen, regenerated cellulose, viscose and cellulose acetate, also natural fibers such as kapok, hemp, wood and wood products such as pressed board, cardboard, batting, paper, wood flour, sawdust and the like.

The modified cellulose according to this invention is a new article of commerce possessing unique properties, outstanding among which are the combination of a cellulosic structure with a hydrophobic character which is not susceptible of removal by exposure to organic solvents.

While this invention has been described with reference to certain specific embodiments and illustrated by certain examples, these are illustrative only, and the invention is not to be construed as limited, except as set forth in the appended claims.

We claim:

1. A method for the treatment of a fibrous cellulosic textile material, at least one-fifteenth of the hydroxymethyl groups originally present in said material being present in unsubstituted form, which comprises the steps of partially carboxyalkylating said cellulosic material under non-dissolving conditions, to maintain the fibrous form, to the extent that between one-third and onefifteenth of the hydroxymethyl groups originally present in said cellulosic material are converted to carboxyalkoxymethyl groups and treating said non-dissolved, partially carboxyalkylated cellulose with a quaternary ammonium halide having at least one alkyl group containing from 12 to 18 carbon atoms.

2. A method according to claim 1, wherein said quaternary ammonium halide is dodecyl trimethylamrnonium chloride.

3. A method according to claim 1, wherein said quaternary ammonium halide is tetradecyl triethylammoniurn bromide.

4. A method according to claim 1, wherein said quaternary ammonium halide is dioctadecyl dimethylammonium iodide.

5. As a new article of manufacture, a modified cellulosic textile material characterized in that between onethird and one-fifteenth of the original anhydro-glucose units of said cellulose are representable by the formula wherein R represents a divalent alkyl hydrocarbon radical containing from 1 to 5 carbon atoms and the four R groups are monovalent alkyl hydrocarbon radicals which may be the same or difierent, each R group containing from 1 to 18 carbon atoms, at least one of said R groups containing at least 12 carbon atoms.

6. As a new article of manufacture according to claim 5, a water repellent cellulosic fabric.

7. As a new article of manufacture according to claim 5, a modified cellulosic material, wherein the modified anhydroglucose units are stable in the presence of organic solvents and of water.

References Cited in the file of this patent UNITED STATES PATENTS 2,313,741 Engelmann et al Mar. 16, 1943 2,314,277 Hurd Mar. 16, 1943 2,448,153 Reid et al. Aug. 31, 1948 2,681,846 Guthrie et al. June 22, 1954 2,729,535 Balassa et al. Jan. 3, 1956 2,840,446 Compton et al. June 24, 1958 

1. A METHOD FOR THE TREATMENT OF A FIBROUS CELLULOSIC TEXTILE MATERIAL, AT LEAST ONE-FIFTEENTH OF THE HYDROXYMETHYL GROUPS ORIGINALLY PRESENT IN SAID MATERIAL BEING PRESENT IN UNSUBSTITUTED FORM, WHICH COMPRISES THE STEPS OF PARTIALLY CARBOXYALKYLATING SAID CELLULOSIC MATERIAL UNDER NON-DISSOLVING CONDITIONS, TO MAINTAIN THE FIBROUS FORM, TO THE EXTENT THAT BETWEEN ONE-THIRD AND ONEFIFTEENTH OF THE HYDROXYMETHYL GROUPS ORIGINALLY PRESENT IN SAID CELLULOSIC MATERIAL ARE CONVERTED TO CARBOXYALKOXYMETHYL GROUPS AND TREATING SAID NON-DISSOLVED, PARTIALLY CARBOXYALKYLATED CELLULOSE WITH A QUATERNARY AMMONIUM HALIDE HAVING AT LEAST ONE ALKYL GROUP CONTAINING FROM 12 TO 18 CARBON ATOMS. 